As people carry out their daily routine activities, they take risks that they usually underestimate. Whether driving a car, crossing a road, taking a walk or climbing a mountain, a person performing any of these activities may end up in an accident. For elderly or sick people, they can be the subject of a personal emergency event even when staying at home. In case of personal emergency, detecting such events on time usually allows for fast and proper help or rescue to be provided to the people at risk. However, when a person undergoes a personal emergency while alone or in a secluded location, detecting the emergency event by others may become less likely, and, therefore, the person is less likely to receive proper help on time. Furthermore, research has shown that when many people witness an emergency event, they very often assume somebody else will call to report the emergency event to emergency service providers (e.g., police, fire department, hospital, etc.). Such behavior reduces the probability of a timely report of an incident, to some extent, by an amount proportional to the number of people witnessing the emergency event.
Some existing emergency detection/response systems make it easier for a person undergoing a personal emergency at home to seek help. For example, the personal emergency response system (PERS) provides a device that can be connected to an emergency switchboard through a phone line. A person undergoing a personal emergency event at home (such an elderly or sick person falling while alone) can initiate a call for help by pressing a button on such a device.